The port->port.tty maybe reset as NULL, If gs_close() was invoked unexpectedly during running gserial_connect(). BUG: KASAN: null-ptr-deref in tty_wakeup+0x1c/0x84 Call trace: [<0000000095c3c837>] dump_backtrace+0x0/0x6d4 [<0000000047726bb8>] show_stack+0x18/0x20 [<00000000bedb4c1e>] --dump_stack+0x20/0x28 [<00000000722f2e2a>] dump_stack+0x84/0xb0 [<00000000325683d4>] kasan_report_error+0x178/0x1e4 [<0000000053079998>] kasan_report_error+0x0/0x1e4 [<00000000b6d33afa>] --asan_load8+0x150/0x15c [<00000000188745b8>] tty_wakeup+0x1c/0x84 [<0000000064f6dd21>] gs_start_io+0xd0/0x11c [<0000000063d67b6c>] gserial_connect+0x15c/0x1b0 [<00000000faf7c0f9>] dm_set_alt+0xa8/0x190 [<000000008deb1909>] composite_setup+0xde4/0x1edc [<00000000792ee16d>] android_setup+0x210/0x294 [<00000000ab32ef30>] dwc3_ep0_delegate_req+0x48/0x68 [<0000000054e26fd2>] dwc3_ep0_interrupt+0xf2c/0x16fc [<0000000050cb2262>] dwc3_interrupt+0x464/0x1f44 [<00000000fdcaa6e9>] --handle_irq_event_percpu+0x184/0x398 [<000000003b24ff56>] handle_irq_event_percpu+0xa0/0x134 [<00000000aedda5ee>] handle_irq_event+0x60/0xa0 [<000000005f51a570>] handle_fasteoi_irq+0x23c/0x31c [<000000008db2608d>] generic_handle_irq+0x70/0xa4 [<00000000098683fc>] --handle_domain_irq+0x84/0xe0 [<000000008ed23b46>] gic_handle_irq+0x98/0xb8 Signed-off-by: Li Tao <tao.li@vivo.com> --- drivers/usb/gadget/function/u_serial.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index 8167d379e115..3c109a8f9ec4 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -565,7 +565,8 @@ static int gs_start_io(struct gs_port *port) gs_start_tx(port); /* Unblock any pending writes into our circular buffer, in case * we didn't in gs_start_tx() */ - tty_wakeup(port->port.tty); + if (port->port.tty) + tty_wakeup(port->port.tty); } else { gs_free_requests(ep, head, &port->read_allocated); gs_free_requests(port->port_usb->in, &port->write_pool, -- 2.17.1
On Wed, Mar 18, 2020 at 10:56:01AM +0800, Li Tao wrote:
> The port->port.tty maybe reset as NULL, If gs_close() was invoked
> unexpectedly during running gserial_connect().
>
> BUG: KASAN: null-ptr-deref in tty_wakeup+0x1c/0x84
> Call trace:
> [<0000000095c3c837>] dump_backtrace+0x0/0x6d4
> [<0000000047726bb8>] show_stack+0x18/0x20
> [<00000000bedb4c1e>] --dump_stack+0x20/0x28
> [<00000000722f2e2a>] dump_stack+0x84/0xb0
> [<00000000325683d4>] kasan_report_error+0x178/0x1e4
> [<0000000053079998>] kasan_report_error+0x0/0x1e4
> [<00000000b6d33afa>] --asan_load8+0x150/0x15c
> [<00000000188745b8>] tty_wakeup+0x1c/0x84
> [<0000000064f6dd21>] gs_start_io+0xd0/0x11c
> [<0000000063d67b6c>] gserial_connect+0x15c/0x1b0
> [<00000000faf7c0f9>] dm_set_alt+0xa8/0x190
> [<000000008deb1909>] composite_setup+0xde4/0x1edc
> [<00000000792ee16d>] android_setup+0x210/0x294
> [<00000000ab32ef30>] dwc3_ep0_delegate_req+0x48/0x68
> [<0000000054e26fd2>] dwc3_ep0_interrupt+0xf2c/0x16fc
> [<0000000050cb2262>] dwc3_interrupt+0x464/0x1f44
> [<00000000fdcaa6e9>] --handle_irq_event_percpu+0x184/0x398
> [<000000003b24ff56>] handle_irq_event_percpu+0xa0/0x134
> [<00000000aedda5ee>] handle_irq_event+0x60/0xa0
> [<000000005f51a570>] handle_fasteoi_irq+0x23c/0x31c
> [<000000008db2608d>] generic_handle_irq+0x70/0xa4
> [<00000000098683fc>] --handle_domain_irq+0x84/0xe0
> [<000000008ed23b46>] gic_handle_irq+0x98/0xb8
>
> Signed-off-by: Li Tao <tao.li@vivo.com>
> ---
> drivers/usb/gadget/function/u_serial.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> index 8167d379e115..3c109a8f9ec4 100644
> --- a/drivers/usb/gadget/function/u_serial.c
> +++ b/drivers/usb/gadget/function/u_serial.c
> @@ -565,7 +565,8 @@ static int gs_start_io(struct gs_port *port)
> gs_start_tx(port);
> /* Unblock any pending writes into our circular buffer, in case
> * we didn't in gs_start_tx() */
> - tty_wakeup(port->port.tty);
> + if (port->port.tty)
> + tty_wakeup(port->port.tty);
What prevents port.tty from being set to NULL between the check and the
call to tty_wakeup?
Shouldn't gs_close() and gserial_connect() have some sort of locking to
prevent this?
thanks,
greg k-h
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Date: 2020-03-18 18:12:40 To: Li Tao <tao.li@vivo.com> Cc: Felipe Balbi <balbi@kernel.org>,"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,Sergey Organov <sorganov@gmail.com>,linux-usb@vger.kernel.org,linux-kernel@vger.kernel.org,wenhu.wang@vivo.com Subject: Re: [PATCH] usb: gadget: serial: Fixed KASAN null-ptr-deref in tty_wakeup>On Wed, Mar 18, 2020 at 10:56:01AM +0800, Li Tao wrote: >> The port->port.tty maybe reset as NULL, If gs_close() was invoked >> unexpectedly during running gserial_connect(). >> >> BUG: KASAN: null-ptr-deref in tty_wakeup+0x1c/0x84 >> Call trace: >> [<0000000095c3c837>] dump_backtrace+0x0/0x6d4 >> [<0000000047726bb8>] show_stack+0x18/0x20 >> [<00000000bedb4c1e>] --dump_stack+0x20/0x28 >> [<00000000722f2e2a>] dump_stack+0x84/0xb0 >> [<00000000325683d4>] kasan_report_error+0x178/0x1e4 >> [<0000000053079998>] kasan_report_error+0x0/0x1e4 >> [<00000000b6d33afa>] --asan_load8+0x150/0x15c >> [<00000000188745b8>] tty_wakeup+0x1c/0x84 >> [<0000000064f6dd21>] gs_start_io+0xd0/0x11c >> [<0000000063d67b6c>] gserial_connect+0x15c/0x1b0 >> [<00000000faf7c0f9>] dm_set_alt+0xa8/0x190 >> [<000000008deb1909>] composite_setup+0xde4/0x1edc >> [<00000000792ee16d>] android_setup+0x210/0x294 >> [<00000000ab32ef30>] dwc3_ep0_delegate_req+0x48/0x68 >> [<0000000054e26fd2>] dwc3_ep0_interrupt+0xf2c/0x16fc >> [<0000000050cb2262>] dwc3_interrupt+0x464/0x1f44 >> [<00000000fdcaa6e9>] --handle_irq_event_percpu+0x184/0x398 >> [<000000003b24ff56>] handle_irq_event_percpu+0xa0/0x134 >> [<00000000aedda5ee>] handle_irq_event+0x60/0xa0 >> [<000000005f51a570>] handle_fasteoi_irq+0x23c/0x31c >> [<000000008db2608d>] generic_handle_irq+0x70/0xa4 >> [<00000000098683fc>] --handle_domain_irq+0x84/0xe0 >> [<000000008ed23b46>] gic_handle_irq+0x98/0xb8 >> >> Signed-off-by: Li Tao <tao.li@vivo.com> >> --- >> drivers/usb/gadget/function/u_serial.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c >> index 8167d379e115..3c109a8f9ec4 100644 >> --- a/drivers/usb/gadget/function/u_serial.c >> +++ b/drivers/usb/gadget/function/u_serial.c >> @@ -565,7 +565,8 @@ static int gs_start_io(struct gs_port *port) >> gs_start_tx(port); >> /* Unblock any pending writes into our circular buffer, in case >> * we didn't in gs_start_tx() */ >> - tty_wakeup(port->port.tty); >> + if (port->port.tty) >> + tty_wakeup(port->port.tty); > >What prevents port.tty from being set to NULL between the check and the >call to tty_wakeup? > >Shouldn't gs_close() and gserial_connect() have some sort of locking to >prevent this? > I encountered this issue on Samsung EXYNOS980 platform, Maybe this is platform specific issue. The USB interrupt handler got port_lock on CPU 0 in gserial_connect while gs_close is waiting for this lock on CPU 1. But this port_lock will unlock in gs_start_io-->gs_start_rx temporarily, This race condition may cause port.tty set as NULL. >thanks, > >greg k-h
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Date: 2020-03-18 18:12:40 To: Li Tao <tao.li@vivo.com> Cc: Felipe Balbi <balbi@kernel.org>,"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,Sergey Organov <sorganov@gmail.com>,linux-usb@vger.kernel.org,linux-kernel@vger.kernel.org,wenhu.wang@vivo.com Subject: Re: [PATCH] usb: gadget: serial: Fixed KASAN null-ptr-deref in tty_wakeup>On Wed, Mar 18, 2020 at 10:56:01AM +0800, Li Tao wrote: >> The port->port.tty maybe reset as NULL, If gs_close() was invoked >> unexpectedly during running gserial_connect(). >> >> BUG: KASAN: null-ptr-deref in tty_wakeup+0x1c/0x84 >> Call trace: >> [<0000000095c3c837>] dump_backtrace+0x0/0x6d4 >> [<0000000047726bb8>] show_stack+0x18/0x20 >> [<00000000bedb4c1e>] --dump_stack+0x20/0x28 >> [<00000000722f2e2a>] dump_stack+0x84/0xb0 >> [<00000000325683d4>] kasan_report_error+0x178/0x1e4 >> [<0000000053079998>] kasan_report_error+0x0/0x1e4 >> [<00000000b6d33afa>] --asan_load8+0x150/0x15c >> [<00000000188745b8>] tty_wakeup+0x1c/0x84 >> [<0000000064f6dd21>] gs_start_io+0xd0/0x11c >> [<0000000063d67b6c>] gserial_connect+0x15c/0x1b0 >> [<00000000faf7c0f9>] dm_set_alt+0xa8/0x190 >> [<000000008deb1909>] composite_setup+0xde4/0x1edc >> [<00000000792ee16d>] android_setup+0x210/0x294 >> [<00000000ab32ef30>] dwc3_ep0_delegate_req+0x48/0x68 >> [<0000000054e26fd2>] dwc3_ep0_interrupt+0xf2c/0x16fc >> [<0000000050cb2262>] dwc3_interrupt+0x464/0x1f44 >> [<00000000fdcaa6e9>] --handle_irq_event_percpu+0x184/0x398 >> [<000000003b24ff56>] handle_irq_event_percpu+0xa0/0x134 >> [<00000000aedda5ee>] handle_irq_event+0x60/0xa0 >> [<000000005f51a570>] handle_fasteoi_irq+0x23c/0x31c >> [<000000008db2608d>] generic_handle_irq+0x70/0xa4 >> [<00000000098683fc>] --handle_domain_irq+0x84/0xe0 >> [<000000008ed23b46>] gic_handle_irq+0x98/0xb8 >> >> Signed-off-by: Li Tao <tao.li@vivo.com> >> --- >> drivers/usb/gadget/function/u_serial.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c >> index 8167d379e115..3c109a8f9ec4 100644 >> --- a/drivers/usb/gadget/function/u_serial.c >> +++ b/drivers/usb/gadget/function/u_serial.c >> @@ -565,7 +565,8 @@ static int gs_start_io(struct gs_port *port) >> gs_start_tx(port); >> /* Unblock any pending writes into our circular buffer, in case >> * we didn't in gs_start_tx() */ >> - tty_wakeup(port->port.tty); >> + if (port->port.tty) >> + tty_wakeup(port->port.tty); > >What prevents port.tty from being set to NULL between the check and the >call to tty_wakeup? > >Shouldn't gs_close() and gserial_connect() have some sort of locking to >prevent this? > I encountered this issue on Samsung EXYNOS980 platform, Maybe this is platform specific issue. The USB interrupt handler got port_lock on CPU 0 in gserial_connect while gs_close is waiting for this lock on CPU 1. But this port_lock will unlock in gs_start_io-->gs_start_rx temporarily, This race condition may cause port.tty set as NULL. greg k-h, Do you have some good suggestions? >thanks, > >greg k-h